Main conventional parameters to detect or diagnose nephritis using the urine sample include the presence and/or level of a protein, albumin, type IV collagen (three chains-domain) and β 2M etc. Further, conventional definite diagnostic method for nephritis depends on a method of staining renal slice samples obtained by renal biopsy in order to observe the deposit of immunoglobulin (hereafter referred to as Ig) or formation of crescents. For example, in order to diagnose IgA nephropathy, detecting “granular deposit of IgA mainly in diffused mesangial region of kidney” may need to be done, for example, as described in p. 1071 of Laboratory Examination (2001˜2002; published by BUNKO-DO). The foregoing detecting granular deposit of IgA can be done by an immunofluorescence assay or enzyme immunoassay, however, it may necessarily require the renal biopsy procedures.